docs: def close(self):
          """
          Iterate through all of the connections and close each one.
          """
          if not self._closed:
              self._closed = True
              self._stop_multi_pools()
              if self._http_pool is not None:
                  self._http_pool.clear()
                  self._http_pool = None
              if self._tcp_pool is not None:
                  self._tcp_pool.clear()
                  self._tcp_pool = None